The Tor Browser: mobile/android/base/home/SimpleCursorLoader.java@fc2d59ddac77

     1 /*

     2  * This is an adapted version of Android's original CursorLoader

     3  * without all the ContentProvider-specific bits.

     4  *

     5  * Copyright (C) 2011 The Android Open Source Project

     6  *

     7  * Licensed under the Apache License, Version 2.0 (the "License");

     8  * you may not use this file except in compliance with the License.

     9  * You may obtain a copy of the License at

    10  *

    11  *      http://www.apache.org/licenses/LICENSE-2.0

    12  *

    13  * Unless required by applicable law or agreed to in writing, software

    14  * distributed under the License is distributed on an "AS IS" BASIS,

    15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

    16  * See the License for the specific language governing permissions and

    17  * limitations under the License.

    18  */

    20 package org.mozilla.gecko.home;

    22 import android.content.Context;

    23 import android.database.Cursor;

    24 import android.support.v4.content.AsyncTaskLoader;

    26 abstract class SimpleCursorLoader extends AsyncTaskLoader<Cursor> {

    27     final ForceLoadContentObserver mObserver;

    28     Cursor mCursor;

    30     public SimpleCursorLoader(Context context) {

    31         super(context);

    32         mObserver = new ForceLoadContentObserver();

    33     }

    35     /**

    36      * Loads the target cursor for this loader. This method is called

    37      * on a worker thread.

    38      */

    39     protected abstract Cursor loadCursor();

    41     /* Runs on a worker thread */

    42     @Override

    43     public Cursor loadInBackground() {

    44         Cursor cursor = loadCursor();

    46         if (cursor != null) {

    47             // Ensure the cursor window is filled

    48             cursor.getCount();

    49             cursor.registerContentObserver(mObserver);

    50         }

    52         return cursor;

    53     }

    55     /* Runs on the UI thread */

    56     @Override

    57     public void deliverResult(Cursor cursor) {

    58         if (isReset()) {

    59             // An async query came in while the loader is stopped

    60             if (cursor != null) {

    61                 cursor.close();

    62             }

    64             return;

    65         }

    67         Cursor oldCursor = mCursor;

    68         mCursor = cursor;

    70         if (isStarted()) {

    71             super.deliverResult(cursor);

    72         }

    74         if (oldCursor != null && oldCursor != cursor && !oldCursor.isClosed()) {

    75             oldCursor.close();

    76         }

    77     }

    79     /**

    80      * Starts an asynchronous load of the list data. When the result is ready the callbacks

    81      * will be called on the UI thread. If a previous load has been completed and is still valid

    82      * the result may be passed to the callbacks immediately.

    83      *

    84      * Must be called from the UI thread

    85      */

    86     @Override

    87     protected void onStartLoading() {

    88         if (mCursor != null) {

    89             deliverResult(mCursor);

    90         }

    92         if (takeContentChanged() || mCursor == null) {

    93             forceLoad();

    94         }

    95     }

    97     /**

    98      * Must be called from the UI thread

    99      */

   100     @Override

   101     protected void onStopLoading() {

   102         // Attempt to cancel the current load task if possible.

   103         cancelLoad();

   104     }

   106     @Override

   107     public void onCanceled(Cursor cursor) {

   108         if (cursor != null && !cursor.isClosed()) {

   109             cursor.close();

   110         }

   111     }

   113     @Override

   114     protected void onReset() {

   115         super.onReset();

   117         // Ensure the loader is stopped

   118         onStopLoading();

   120         if (mCursor != null && !mCursor.isClosed()) {

   121             mCursor.close();

   122         }

   124         mCursor = null;

   125     }

   126 }

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